In 1956, Marlowe appeared as Knox Cutler in the western film The Young Guns. In 1958, he began appearing in a number of television westerns, with his guest role of Jess "Little Elk" Carswell on NBC's Wagon Train with Ward Bond. In 1959, he portrayed the outlaw John Wesley Hardin, who reportedly killed 44 men in the Old West, in the episode "The Turning Point" of ABC's Bronco.[4]

In the 1960s, Marlowe continued to appear in drama and adventure series, often as a young man in trouble with the law or unwilling to adjust to societal mores. He appeared twice in 1961 on ABC's Target: The Corruptors! in episodes "A Man's Castle" (as Tito) and "Mr. Meglomania" (as Phil Manzak).[4] In 1961, he starred as Armand Fontaine a serial killer on the episode "Effigy in Snow" of CBS's Route 66. He guest starred as Eliot Gray in the 1961 episode "The Throwback" of CBS's Alfred Hitchcock Presents. He appeared on Thriller, Dr. Kildare, and The Detectives.[4]

During the 1990s, Marlowe appeared as Al Brackman twice on Matlock, on Father Dowling Mysteries and on Jake and the Fatman. His most enduring work in the decade was in 1994 with 65 appearances as Michael Burke on the night-time soap opera Valley of the Dolls. In 1995, he appeared as Avery Nugent in the episode "School for Murder" on Murder, She Wrote.[4]